Earlier quoted context omitted.
Use MakeMKV to pull an MKV off the disc, then use Handbrake to compress it to a reasonable size. Relatively easy, just takes a bit.
I thought blu-ray decoding was not possible. I remember long ago the DVD keys were extracted but it became impossible for blu-ray, except with a modified blu-ray disk drive with an older firmware that enabled this.
I haven't bought new movies lately, but I've been able to rip all the blu-rays I currently own with my old Blu-Ray drive.